The only number I could find was 22/27 hours of video playback for 16/16 Pro, you can compare that to older models on https://www.apple.com/iphone/compare/ that might give some indication?
"The new mechanical architecture improves heat dissipation and efficiency for up to 20 percent better sustained performance. Along with the new internal design and advanced power management of iOS 18, larger batteries are optimized to offer a huge leap in battery life."
>larger batteries
>optimized
> a huge leap in battery life
This is still all just marketing puff and air though.
Also 20% better than what?
This is designed so that when you try to nail them down, they can change what it is 20% better than.